The Information Commissioner’s Office (ICO) estimates that TikTok allowed up to 1.4 million UK children under 13 to use its platform in 2020, despite its own rules not allowing children that age to create an account.

The UK General Data Protection Regulation (UK GDPR) provides that organisations which use personal data when offering information society services to children under 13 must have consent from their parents or carers.

The ICO said TikTok failed to do that, even though it ought to have been aware that under 13s were using its platform. TikTok also failed to carry out adequate checks to identify and remove underage children from its platform.

The ICO investigation found that a concern was raised internally with some senior employees about children under 13 using the platform and not being removed. In the ICO’s view TikTok did not respond adequately.

The £12.7 million fine announced yesterday is significantly lower than the £27 million originally suggested by the regulator in a “notice of intent” issued last year.

John Edwards, the UK information commissioner, said: “There are laws in place to make sure our children are as safe in the digital world as they are in the physical world. TikTok did not abide by those laws.

“As a consequence, an estimated one million under-13s were inappropriately granted access to the platform, with TikTok collecting and using their personal data. That means that their data may have been used to track them and profile them, potentially delivering harmful, inappropriate content at their very next scroll.

“TikTok should have known better. TikTok should have done better. Our £12.7m fine reflects the serious impact their failures may have had. They did not do enough to check who was using their platform or take sufficient action to remove the underage children that were using their platform.”

A spokesperson for TikTok told the BBC: “While we disagree with the ICO’s decision, which relates to May 2018–July 2020, we are pleased that the fine announced today has been reduced to under half the amount proposed last year. We will continue to review the decision and are considering next steps.”